AmphibiaReptilia

AmphibiaReptilia is a traditional, informal grouping used to refer collectively to the two major land-dwelling tetrapod lineages: Amphibia and Reptilia. It is not a formal clade in modern cladistics, but a convenience term employed in some textbooks and discussions to compare amphibian and reptilian biology and evolution, especially their adaptations to terrestrial life.

Extant Amphibia includes frogs and toads (order Anura), salamanders and newts (order Urodela or Caudata), and caecilians (order Gymnophiona). Extant Reptilia includes turtles (Testudines), lizards and snakes (Squamata), and crocodilians (Crocodilia). Birds and mammals are excluded from AmphibiaReptilia as they belong to other major tetrapod groups.

Evolutionary context: The grouping reflects convergent terrestrial adaptations that arose independently in amphibians and reptiles after their split from a common aquatic ancestor. Reptiles developed amniotic eggs, waterproof skin, and improved water conservation, while many amphibians retained aquatic reproduction and permeable skin, contributing to different life cycles.

Fossil evidence places the amphibian–reptile split among early amniotes in the late Paleozoic, with modern diversity totaling roughly 8,000 amphibian species and about 11,000 reptile species. The term is largely historical and used mainly in educational contexts or comparative anatomy discussions.